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Lateral patellar retinaculum

The lateral patellar retinaculum is a fibrous band of connective tissue that extends from the quadriceps tendon and patella laterally to blend with the iliotibial band and tibia. It acts as part of the extensor apparatus of the knee, contributing to patellar stability and alignment. It plays a significant role in patellofemoral tracking, and abnormalities in its tightness or injury are implicated in patellar maltracking and anterior knee pain syndromes.

Synonyms

  • Lateral retinaculum of knee

  • Lateral patellar stabilizing retinaculum

  • Lateral patellofemoral retinacular fibers

Origin and Insertion

  • Origin: Fibrous expansions from:

    • Quadriceps tendon (especially vastus lateralis)

    • Iliotibial band

    • Lateral intermuscular septum

  • Course: Fibers pass laterally and inferiorly from the patella and quadriceps, forming a broad fibrous sheet

  • Insertion:

    • Anterolateral aspect of the tibia (Gerdy’s tubercle region)

    • Patella (lateral border)

    • Patellar tendon sheath

Relations

  • Anteriorly: Subcutaneous tissue and skin of the knee

  • Posteriorly: Lateral patellofemoral ligament, lateral meniscus, joint capsule

  • Medially: Patella and patellar tendon

  • Laterally: Iliotibial band and vastus lateralis muscle

Nerve Supply

  • Supplied indirectly via branches innervating the knee joint capsule (femoral and tibial nerves through articular branches)

Arterial Supply

  • Genicular branches of the popliteal artery

  • Lateral superior and inferior genicular arteries

Venous Drainage

  • Corresponding genicular veins into the popliteal vein

Function

  • Provides lateral stabilization of the patella

  • Resists excessive medial displacement of the patella

  • Contributes to patellofemoral tracking during knee flexion and extension

  • Functions as part of the knee extensor mechanism

Clinical Significance

  • Tight lateral retinaculum: Can cause patellar maltracking, anterior knee pain, or lateral patellar tilt

  • Lateral release surgery: Performed in refractory patellofemoral pain or instability cases

  • Injury: Trauma or surgery can weaken retinaculum, predisposing to patellar instability

  • Imaging relevance: MRI helps assess thickening, tears, scarring, or abnormal tension

MRI Appearance

T1-weighted images:

  • Appears as a low-signal-intensity fibrous band

  • Surrounded by bright subcutaneous fat and adjacent muscle

T2-weighted images:

  • Normal retinaculum shows dark low signal

  • Injury, edema, or strain shows focal bright hyperintense signal within or adjacent to fibers

STIR (Short Tau Inversion Recovery):

  • Retinaculum normally dark

  • Injuries, inflammation, or scarring appear bright hyperintense

Proton Density Fat-Saturated (PD FS):

  • Normal retinaculum: dark low signal

  • Pathology: bright signal intensity from edema, tear, or scarring

T1 Fat-Sat Post-Contrast:

  • Normal: mild or no enhancement

  • Pathology (inflammation, scarring, tumor infiltration): focal or diffuse enhancement

CT Appearance

Non-Contrast CT:

  • Retinaculum not easily visualized directly; appears as a thin soft tissue band along the lateral patella

  • Thickening or calcification may be seen in chronic pathology

  • Fat planes define its course

Post-Contrast CT:

  • Retinaculum itself enhances minimally

  • Pathologic processes (inflammation, tumor infiltration) may show irregular thickening or enhancement

  • Surrounding fat may show stranding in inflammation

MRI images

Lateral patellar retinaculum sag cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI images

lateral patellar retinaculum anatomy image mri 3t

MRI images

Lateral patellar retinaculum axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI image

lateral patellar retinaculum anatomy image

CT image

Lateral patellar retinaculum ct axial iamge

CT image

Lateral patellar retinaculum ct sagittal image